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Re: proced: ppid of process ID 0 can be 0
From: |
Roland Winkler |
Subject: |
Re: proced: ppid of process ID 0 can be 0 |
Date: |
Sat, 20 Dec 2008 23:41:00 +0100 |
On Sun Dec 21 2008 Eli Zaretskii wrote:
> > I mean, it seems to me that ultimately the solution is always the
> > same: when using the ppid attribute, one needs to make sure that it
> > is different from the corresponding pid. Or could one assign a
> > special meaning to the case that ppid=pid? There is no doubt that
> > proced assumes that ppid is always different from pid.
>
> Why do you need to assume that? Is that only to determine whether a
> given process is the root of the process tree? If so, a more portable
> way of doing that would be to have a primitive for that with a
> system-dependent implementation.
It's the definition of a tree: when A points back to A, this doesn't
give a process tree. Of course, as I said, for Proced it is not so
important whether system-process-attributes can return a ppid that
equals pid or whether in this case it returns no ppid attribute
(or a ppid=0). It's easy to handle this case on te level of proced.
Yet the current discussion suggests to me that it would be
advantageous if the behavior of system-process-attributes was
documented for this case. It seems to me that the possiblities are:
- it may return a ppid that equals pid, so that one needs to handle
this case appropriately, if necessary, on the lisp level,
- it may return no ppid, if strictly speaking there is no parent
process
- it may return a ppid of zero, which is the current behavior under
GNU/linux
- some or all the above options are "legal" and its up to the user
to handle these possibilities appropriately
Is there any possiblity missing?
Roland
- proced: ppid of process ID 0 can be 0, Juanma Barranquero, 2008/12/19
- Re: proced: ppid of process ID 0 can be 0, Stefan Monnier, 2008/12/19
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/20
- Re: proced: ppid of process ID 0 can be 0, Roland Winkler, 2008/12/20
- Re: proced: ppid of process ID 0 can be 0, Juanma Barranquero, 2008/12/20
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/20
- Re: proced: ppid of process ID 0 can be 0,
Roland Winkler <=
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/20
- Re: proced: ppid of process ID 0 can be 0, Roland Winkler, 2008/12/20
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/21
- Re: proced: ppid of process ID 0 can be 0, Juanma Barranquero, 2008/12/21
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/21
- Re: proced: ppid of process ID 0 can be 0, Juanma Barranquero, 2008/12/22
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/22
- Re: proced: ppid of process ID 0 can be 0, Juanma Barranquero, 2008/12/22
- Re: proced: ppid of process ID 0 can be 0, Stefan Monnier, 2008/12/21
- Re: proced: ppid of process ID 0 can be 0, Eli Zaretskii, 2008/12/21